Isoprenoid biosynthesis and regulation

Isoprenoids (also referred to as terpenoids) are derived from a common C5 precursor, isopentenyl diphosphate (IPP) and its allylic isomer dimethylallyl diphosphate (DMAPP). Two separate IPP forming pathways co-exist in plants: the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway provides the precursors for the synthesis of monoterpenes (and among them the monoterpenes leading to the alkaloids from Catharanthus roseus), carotenoids, apocarotenoids the side chain of chlorophylls, tocopherols and prenylquinones, while the mevalonic acid (MVA) pathway leads to precursors for the formation of triterpenes, sesquiterpenes, phytosterols, ubiquinone, vitamin D and primary metabolites important for cell integrity.

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Our research is focused on the elucidation of isoprenoid biosynthesis including the MEP and MVA pathways as well as the next enzymatic steps catalyzed by prenyltransferases and terpene synthases. Moreover, the deciphering of the overall isoprenoid architecture allow us to investigate the regulatory network and to look for transcription factors that would regulate specifically isoprenoid biosynthesis pathway genes and therefore the supply of precursors for alkaloid biosynthesis.

During the past years, we established a map at the subcellular and tissular levels of the isoprenoid biosynthesis pathways highlighting the complexity of localization of isoprenoid enzymes. For example, recent subcellular studies have shown that the peroxisome is an additional isoprenoid biosynthetic compartment within plant cells. Our work also led to the characterization of isoprenoid genes and their expression regulation. We therefore isolated few transcription factors that specifically target the MEP pathway genes.